difference between analog telephone and digtal

[aneesholv]

what is the difference between analog telephone and digtal telephone ? I mean the technology behind these two . Can you also explain the working principle of normal telephone networks (PSTN) from initiate a call to ends that call ?

 

[navenmou]

Hi

Please once see below sites.....
Public switched telephone network - Wikipedia, the free encyclopedia

Between analog and digital is as a technology analog is the process of taking an audio or video signal the human voice and translating it into electronic pulses digital on the other hand is breaking the signal into a binary format where the audio or video data is represented by a series of 1s and 0s.
web.cs.wpi.edu/~cs513/s07/week2-physcont.pdf

 

[ckshivaram]

Enter digital
The newer of the two, digital technology breaks your voice (or television) signal into binary code, a series of 1s and 0s transfers it to the other end where another device (phone, modem or TV) takes all the numbers and reassembles them into the original signal. The beauty of digital is that it knows what it should be when it reaches the end of the transmission. That way, it can correct any errors that may have occurred in the data transfer. What does all that mean to you? Clarity. In most cases, you'll get distortion-free conversations and clearer TV pictures.
You'll get more, too. The nature of digital technology allows it to cram lots of those 1s and 0s together into the same space an analog signal uses. Like your button-rich phone at work or your 200-plus digital cable service, that means more features can be crammed into the digital signal.
Compare your simple home phone with the one you may have at the office. At home you have mute, redial, and maybe a few speed-dial buttons. Your phone at work is loaded with function keys, call transfer buttons, and even voice mail. Now, before audiophiles start yelling at me through their PC screens, yes, analog can deliver better sound quality than digital for now. Digital offers better clarity, but analog gives you richer quality.
But like any new technology, digital has a few shortcomings. Since devices are constantly translating, coding, and reassembling your voice, you won't get the same rich sound quality as you do with analog. And for now, digital is still relatively expensive. But slowly, digital like the VCR or the CD is coming down in cost and coming out in everything from cell phones to satellite dishes.
When you're shopping in the telecom world, you often see products touted as "all digital." Or warnings such as "analog lines only." What does it mean? The basic analog and digital technologies vary a bit in definition depending on how they're implemented.

Phone lines
Analog lines, also referred to as POTS (Plain Old Telephone Service), support standard phones, fax machines, and modems. These are the lines typically found in your home or small office. Digital lines are found in large, corporate phone systems.
How do you tell if the phone line is analog or digital? Look at the back of the telephone connected to it. If you see "complies with part 68, FCC Rules" and a Ringer Equivalence Number (REN), then the phone and the line are analog. Also, look at the phone's dialpad. Are there multiple function keys? Do you need to dial "9" for an outside line? These are indicators that the phone and the line are digital.
A word of caution. Though digital lines carry lower voltages than analog lines, they still pose a threat to your analog equipment. If you're thinking of connecting your phone, modem, or fax machine to your office's digital phone system, DON'T! At the very least, your equipment may not function properly. In the worst case, you could zap your communications tools into oblivion.
How? Let's say you connect your home analog phone to your office's digital line. When you lift the receiver, the phone tries to draw an electrical current to operate. Typically this is regulated by the phone company's central office. Since the typical proprietary digital phone system has no facilities to regulate the current being drawn through it, your analog phone can draw too much current so much that it either fries itself or in rare cases, damages the phone system's line card.
Perhaps the most effective use of the digital versus analog technology is in the booming cellular market. With new phone activations increasing exponentially, the limits of analog are quickly being realized. Digital cellular lets significantly more people use their phones within a single coverage area. More data can be sent and received simultaneously by each phone user. Plus, transmissions are more resistant to static and signal fading. And with the all-in-one phones out now phone, pager, voice mail, internet access digital phones offer more features than their analog predecessors.
Analog's sound quality is still superior as some users with dual-transmission phones will manually switch to analog for better sound when they're not concerned with a crowded coverage area but digital is quickly becoming the norm in the cellular market.
You may have an analog phone at home and call your next door neighbor with the same type of phone but you are still connecting through a digital switch.